How to Merge DataGridView Cell in Winforms

I have some data in a grid that currently displays like this:

------------------
|Hd1| Value  |
------------------
|A  | A1     |
------------------
|A  | A2     |
------------------
|A  | A3     |
------------------
|A  | A4     |
------------------
|B  | B1     |
------------------
|B  | B2     |
------------------
|B  | B3     |
------------------
|B  | B4     |
------------------
|B  | B5     |
------------------
|C  | C1     |
------------------
|C  | C2     |
------------------

I want to make it look like this:

|Hd | Value  |
------------------
|A  | A1     |
    ----------
|   | A2     |
    ----------
|   | A3     |
    ----------
|   | A4     |
------------------
|B  | B1     |
    ----------
|   | B2     |
    ----------
|   | B3     |
    ----------
|   | B4     |
    ----------
|   | B5     |
------------------
|C  | C1     |
    ----------
|   | C2     |
------------------

Is there any way that I can merge these cells? I have tried in many ways also google but did not find any suitable way. If it is possible showing this data another way without using datagridview but the result is the way I have showed, that will also solve my problem.

You must first find a duplicate values

Need to two methods:

bool IsTheSameCellValue(int column, int row)
{
    DataGridViewCell cell1 = dataGridView1[column, row];
    DataGridViewCell cell2 = dataGridView1[column, row - 1];
    if (cell1.Value == null || cell2.Value == null)
    {
       return false;
    }
    return cell1.Value.ToString() == cell2.Value.ToString();
}

in the event, cellpainting:

private void dataGridView1_CellPainting(object sender, DataGridViewCellPaintingEventArgs e)
{
    e.AdvancedBorderStyle.Bottom = DataGridViewAdvancedCellBorderStyle.None;
    if (e.RowIndex < 1 || e.ColumnIndex < 0)
        return;
    if (IsTheSameCellValue(e.ColumnIndex, e.RowIndex))
    {
        e.AdvancedBorderStyle.Top = DataGridViewAdvancedCellBorderStyle.None;
    }
    else
    {
        e.AdvancedBorderStyle.Top = dataGridView1.AdvancedCellBorderStyle.Top;
    }  
}

now in cell formatting:

if (e.RowIndex == 0)
    return;
if (IsTheSameCellValue(e.ColumnIndex, e.RowIndex))
{
    e.Value = "";
    e.FormattingApplied = true;
}

and in form_load:

dataGridView1.AutoGenerateColumns = false;

The DataGridView control has no related properties or methods to merge cells, but you can accomplish the same using custom painting. You can use DataGridView.CellPainting event or override the Paint method.

Plus you will need to override the DataGridView.CellClick, CellEnter, CellFormatting and other methods as well in order to give your DataGridView a full featured functionality. For eg on cell click, the entire merged cell (or group of cells that constitute a merged cell) will have to be custom painted.

You can find some sample code here:

http://social.msdn.microsoft.com/forums/en-US/vbinterop/thread/5b659cbd-7d29-4da4-8b38-5d427c3762e2

http://forums.codeguru.com/showthread.php?415930-DataGridView-Merging-Cells

http://www.codeproject.com/Questions/152113/How-can-i-merge-DataGridView-Rows-Cells-with-Equal

There are some good responses on asp.net but in winforms and for this example(merging same data in columns) it is not defined.

You can use color.transparent to hide the same values in datagridview. even by this code, same rows do not deleted and can be good for matematical calculations. even you can define which columns to merge by your desire sort.

In this way if end of "A" was "A4" and also start of "B" was "A4" those would not be merge. which is Often more desired. (If you do not want this, better use other responses)

MergeGridviewCells(DGV,new int[] {0,1});//For example if you want to merge first columns data/then 3th column and then second column you can use new int[] {0,2,1}

private void MergeGridviewCells(DataGridView DGV, int[] idx)
    {
        DataGridViewRow Prev = null;

        foreach (DataGridViewRow item in DGV.Rows)
        {
            if (Prev != null)
            {
                string firstCellText = string.Empty;
                string secondCellText = string.Empty;

                foreach (int i in idx)
                {                        
                    DataGridViewCell firstCell = Prev.Cells[i];
                    DataGridViewCell secondCell = item.Cells[i];

                    firstCellText = (firstCell != null && firstCell.Value != null ? firstCell.Value.ToString() : string.Empty);
                    secondCellText = (secondCell != null && secondCell.Value != null ? secondCell.Value.ToString() : string.Empty);

                    if (firstCellText == secondCellText)
                    {                           
                        secondCell.Style.ForeColor = Color.Transparent;
                    }
                    else
                    {
                        Prev = item;
                        break;
                    }
                }
            }
            else
            {
                Prev = item;
            }
        }
     }

Preview: